Hot wire controlled swinging vane current intermitter or relay



May 31, 1966 H. VOORMAN, JR

HOT WIRE CONTROLLED SWINGING VANE CURRENT INTERMITTER 0R RELAY 2Sheets-Sheet 1 Filed March 10, 1964 NVENTOR. Min z) /00mz4/g=/f BY @w, MP025614 ATTORNEW May 31, 1966 H. VOORMAN, JR 3,

HOT WIRE CONTROLLED SWINGING VANE CURRENT INTERMITTER OR RELAY FiledMarch 10, 1964 2 Sheets-Sheet 2 ATTORNEYS United States Patent 3,254,178HOT WIRE CONTROLLED SWINGING VANE CURRENT INTERMITTER 0R RELAY HenryVoorman, Jr., Midland Park, N.J., assignor to Tong-Sol Electric Inc., acorporation of Delaware Filed Mar. 10, 1964, Ser. No. 350,753 3 Claims.(Cl. 200-113) -'This invention relates to snap action devices of the hotwire type and comprises a novel type of flasher and thermal relay. Ithas particular reference to a switch means which isself-operating andwhich is substantially independent of the voltage of the electricalsupply.

The present thermal switch described herein is intended primarily forflasher use on automotive turn signals but by slight change in structureor circuit it can be used in many other applications. One of thedifiiculties in all flasher switches in use today resides in the factthat their rate of flashing varies with the applied voltage of thebattery. This results in flashing signal lamps which vary greatly intheir flashing speed depending upon the condition of the battery and thevehicle generator. The present invention employs two pull wires foroperating a rockable member on which is secured a flexible vane. Theconstruction and the circuit arrangements are such that the actiondepends upon the rate of cooling of the pull wires instead of their rateof heating and for this reason a more constant rate of operation isinsured.

The invention comprises a thermal switch which is mounted on a baseframe including upper and lower cross pieces. A rockable member issupported between the cross pieces on a flexible hinge for rockablemovement. The rockable member carries a thin vane of spring metal whichis secured at both ends and is bowed outof the plane of the member. Twoheat expansible pull wires are employed to rock the member and snap thevane. Electrical contacts are secured to one or both sides of the vaneand cooperating stationary contacts are secured to the base for contacttherewith. The operating circuits include the resistance wires, a sourceof potential, and the contacts opened and closed by the movement of theflexible vane. The pull wires are attachedto the rockable memberadjacent the pivoted end thereof to provide relatively large contacttravel for relatively small change in length of controlling wires.

For a better understanding of the present invention, and of specificembodiments thereof, reference is made to the following descriptiontaken in connection with the accompanying drawings.

1,FIG. 1 is a side view, with parts in section, showing the new switch.

7 FIG. 2 is a front view of the switch.

FIG. 3 is a top view of the switch of FIGS. 1 and 2.

. FIG. 4 is a circuit diagram of connections showing use of the switchof FIGS. 1 to 3 as a flasher.

' FIG. 5 is a diagram similar to FIG. 4 but showing a modified circuitincluding a positive pilot.

' .FIG. 6 is a circuit diagram of a thermal relay embodying thisinvention.

' Referring now to FIGURES 1, 2 and 3, the switch comprises a base frame10 which includes an upper cross piece 11 and a lower cross piece 12. Arockable generally C-shaped member 13 has its upper arm secured to theframe by a hinge 14 which may be a flat strip of metal. A vane 15 issecured between the upper and lower arms of the member 13. The vane ismade of thin spring metal and is bowed out of the plane of thesupporting member as shown in the figures; Vane 15 is.provided with acentrally disposed contact 16 on the left side of the vane as viewed inFIG. 1. A cooperating contact 17 is secured to a conductive support 18ice which is mounted on an insulator 19 secured to the base frame 10.(See FIG. 3.)

A contact or stop 20 is positioned on the opposite side of the vane fromthe contact 17. Contact 20 is carried by an arm 22 mounted on the baseframe 10 by means of suitable insulation 23.

Portions 25 and 26 of member 13 are bent outwardly as shown in FIGS. 1and 3 for anchoring resistance pull wires 27 and 28. The lower portionsof the pull wires are secured to similar bent-over portions 30 and 31 ofthe base frame 10. The pull wires 27 and 28 are made ofresistancematerial such as Nichrome and the lower end of each pull wireis insulated from the base frame by an insulating bead.

In the diagram of FIG. 4, showing the device of FIGS. 1 to 3 connectedfor operation as a flasher, the pull wires 27 and 28 have been shownconventionally as resistance elements. A source of potential 32, whichmay be a car carried battery of nominally 12 volts, has its negativeterminal grounded and its positive terminal connected through aswitch 33to fixed contact 17. Signal lamps 34 to be flashed are connected betweenground and the movable end of the member 13 through a flexible lead 35.The lower end of pull wire 27 is connected through a ballast resistor 36to ground and the lower end of pull wire 28 is connected through aballast resistor 37 to contact 17.

Before describing the operation of the circuit upon closure of switch33, the operation of the vane during swing of the frame 13 will bebriefly described. The position of the vane 15 shown in FIGS. 1 and 4corresponds to the maximum tension in the pull ribbon 27. The member 13has been swung counterclockwise and the center of the vane has engagedthe stop 20 snapping the center of the vane into position where contacts16 and 17 are in engagement. When the tension in pull wire 28 is amaximum the lower end of element 13 is swung clockwise, building uppressure between contacts 16 and 17 until the center of the vane snapsin the opposite direction to engage the stop 20. In such position of themember 13 and vane 15 the contacts 16 and 17 are open. With the circuitconnections shown in FIG. 4 it is assumed that the tension in pullribbon 27 has been adjusted to make the normal position of the vane 15that is shown in the drawing, namely, with the contacts 16 and 17 inengagement. If now the switch 33 is closed current flows from the source32 through the contacts 16 and 17 and the vane to the lamps 34 of the:load. The lamps are thereupon lighted. Current also flows from thesource 32 through thecontacts 16 and 17, vane 15 and pull wire 27 andballast resistance 36 to ground. Pull wire 28 and ballast resistance 37are shunted by the vane and contacts 16 and 17. Pull wire the pull wire28 and resistor 37. The current through 1 pull wire 27 and resistor 36is substantially reduced with the result that the wire cools at'the sametime that the wire 28 is heating. Consequently, when the tension of thepull wire 27 reaches a predetermined value the vane will snap back toits initial position closing contacts 16 and 17 and energizing the lamps34 to full brilliance. The cycle thereupon repeats.

As a flasher depends solely upon the cooling of a pull wire and not uponthe temperature of the heated pull wire the speed of operation can bemade substantially independent of the voltage of the source. Actually,unlike hot wire flashers previously known the rate of flashing of theflasher of the invention will slightly decrease with increase of voltagerather than increase as in the usual hot wire flasher. By proper choiceof ballast resistors and of initial tension in the pull wiressubstantially constant rate of flashing over a wide range of voltage sayfrom 11 to 15 volts can be obtained.

Where it is desired to have a positive pilot indication the circuit ofFIG. 5 may be employed. In this embodiment of the invention, a relaywinding 38 is connected between the movable end of the element 13 andthe lamp load, and ballast resistor 36 is omitted and instead the lowerend of pull wire 27 is connected to an armature 39 associated with thewinding 38. A top contact 40 engageable by armature 39 when the windingis energized is connected through a pilot lamp 41 to ground. Theremainder of the circuit of FIG. 5 is the same as that of FIG. 4. Withthis arrangement when the lamps 34 are energized upon closure of switch33, winding 38 is likewise energized to pick up its armature and closethe circuit for the pilot lamp through pull wire 27. Thus, the pilotlamp 41 will flash in unison with the lamps 34 provided both lamps 34are operative. Should one of the lamps 34 be burned out the currentthrough the winding 38 will be insufficient to attract the armature 39.Accordingly, the pilot lamp 41 will not be lighted and current will notflow through pull wire 27. The flasher will then cease to operate andthe positive indication thereof will be given by the absence of lightfrom the pilot lamp 41.

The flasher of FIGS. 1 through 3 may be readily converted to a thermalrelay as will be explained in connection with the diagram of FIG. 6 towhich reference may now be had. In FIG. 6 the only structuraldifferences comprise the insulation of the upper ends of the pull wires27 and 28 from the cross arms 25 and 26, the provision of two fixedcontacts 42 and 43 in place of the stop and the mounting of two contacts44 and 45 on the vane 15 for cooperation, respectively, with thecontacts 42 and 43. In this embodiment of the invention the source 32 isconnected to the lower end of pull wire 28 and the upper end of the pullribbon beyond the insulated mounting in the cross piece 26 is connectedto contact 42. The positive terminal of the source 32 is also connectedthrough a switch 46 and flexible connector to the free end of theelement 13. The lamp load 34 is connected to the fixed contact 43 andcontact 17 is connected through the insulation in arm to the pull wire27. The lower end of the pull wire 27 is grounded.

With this arrangement, when switch 46 is open no current flows throughany part of the circuit as the circuit of the pull wire 28 is open atcontact 42. When the switch 46 is closed current flows through thenormally closed contacts 16 and 17 and pull wire 27 which thereuponexpands and permits pull wire 28 to swing element 13 clockwise to closethe contacts 43 and and contacts 42 and 44. The lamps 34 are thereuponlighted. In this position pull wire 28 is shunted by the vane and theclosed switch 46. Thus as pull wire 28 remains cool while pull wire 27is cooling the device will stay in position for illuminating the lampsuntil and unless switch 46 is open. When the switch is opened currentwill again flow through the pull wire 28 to permit wire 27 to return thevane to the initial position. The time required for the vane to returnto initial position after switch 46 is open will depend upon theresistance of the pull wire 28. If the pull wire is of high resistancethe loadis essentially cut off as soon as switch 46 is open because theresistance of the pull wire is in series with the load. If the pullribbon 28 is of low resistance the load current will continue to flowuntil the vane switches. Thus by varying the magnitudes of theresistances the unit can provide for a rapid pull in with a delayed dropout and instant reset orfor a delayed pull in with a rapid drop out andinstant reset or for both a delayed pull in and a delayed drop out withinstant reset.

In the foregoing description both of the flasher and of the relay thepull wires represented by the reference numerals 27 and 28 have beendescribed as carrying current. Obviously, and particularly in thethermal relay the pull wires can be indirectly heated by means of heaterelements surrounding the pull wires. In the case of the circuit of FIG.6 for example the resistors 27 and 28 can be considered as heaters forthe pull wires and if so insulation for the ends of the pull wires wouldnot be required. Also longer time delays in the relay may be obtained byshrouding the pull Wires in an indirectly heated metal tube or channelwith appropriate thermal mass.

The invention has now been described with reference to two embodimentsthereof. In each embodiment, unlike thermal switches heretofore employedthe functioning depends upon the cooling of a pull wire and not upon theheating of the pull wire. As the structure of the invention is bi-stablethe wire that is being heated can relax completely without any shift inthe position of the vane, the shifting of the vane depending solely uponthe temperature reached by the cooling wire as it cools. This feature ofthe invention is of particular value as heretofore indicated in insuringsubstantial constant speed of flasher operation. Another importantfeature of the invention is the structure whereby the pull wires actthrough lever arms upon the pivoted end of the rockable member. If thepull wires were connected to the free end of the rockable membertheywould have to expand in amounts equivalent to the movement of the freeend. With the described instruction relatively a small elongation yieldsa large contact travel.

The following is claimed:

1. A flasher comprising a fixed support, a movable member with one endpivoted on the fixed support, a bowed vane mounted on said movablemember and carrying an electrical contact on one side, a first stopmeans facing the bowed vane and carrying an electrical contact forengagement with the electrical contact on the bowed vane, a second stopmeans facing the other side of the bowed vane, a first pull meansconnected between the fixed support and the movable member at a pointadjacent the pivoted end of the movable member to exert a force on themovable member which can be decreased by heating the first pull meanswith electric current and which tends to pivot the movable member awayfrom the first pull means, .a second pull means connected between thefixed support and the movable member at a point adjacent the pivoted endof the movable member to exert a force on the movable member which canbe decreased by heating the second pull means with electric current andwhich opposes the force exerted on the movable member by the first pullmeans, a source of electric current connecting in series with the firstand second pull means for heating the same, said contacts, when inengagement, shunting said second pull means to cause an alternateheating and cooling of the first and second pull means out of phase witheach other and thereby alternately reverse the bow in the vane byalternately building up pressure between the bow and the first andsecond stops, and a lamp load connected in series with said electriccontacts across said source of electric current so that said lamp loadwill flash on and off.

2. The-thermal switch of claim 1 including arms extending out inopposite directions from said movable member and wherein the point wherethe first pull means is mounted on the movable member is one of saidarms and the point where the second pull means is mounted on the othermovable member is the other of said arms.

3. A thermal switch comprising a fixed support, a movable member withone end pivoted on the fixed support, an electrically conducting bowedvane mounted on said movable member and carrying a first electricalcontact on one side thereof, and second and third electrical contacts onits other side, a first stop means facing the one side of the bowed vaneand carrying an electrical contact which contacts the first electricalcontact on the bowed vane, a second stop means facing the other side ofthe bowed vane and carrying two electrically isolated electricalcontacts which are respectively aligned with the second and thirdelectrical contacts on the bowed vane, a first pull means connectedbetween the fixed support and the movable member at a point adjacent thepivoted end of the movable member to exert a force on the movable memberwhich can be decreased by heating the first pull means with electriccurrent and which tends, when cold, to pivot the movable member towardsthe second means, a second pull means connected between the fixedsupport and the movable member at a point adjacent the pivoted end ofthe movable member to exert force on the movable member which can bedecreased by heating the second pull means with electric current andwhich opposes the force exerted on the movable member by the first pullmeans, a source of electric current, circuit means including said firs-tcontact and the contact on said first stop means, for connecting saidelectrically conductive vane and the said first pull means across saidsource, said second pull means being connected between pull means isreduced, said movable member is moved by said second pull means to snapand how the vane into a position to bridge said isolated contacts, shuntsaid second pull means, energize said load and open the circuit of saidfirst pull means, thereby said load remaining energized until saidswitch means is opened.

References Cited by the Examiner UNITED STATES PATENTS 2,25 6,499 9/1941 Schmidinger ZOO-11?! 2,308,522 1/1943 Leuthold 2001l3 2,355,2968/1944 Holmes 200-137 X FOREIGN PATENTS 1,115,160 4/1956 France.

BERNARD A. GILHEANY, Primary Examiner.

LAURENCE A. WRIGHT, Assistant Examiner.

1. A FLASHER COMPRISING A FIXED SUPPORT, A MOVABLE MEMBER WITH ONE ENDPIVOTED ON THE FIXED SUPPORT, A BOWED VANE MOUNTED ON SAID MOVABLEMEMBER AND CARRY ING AN ELECTRICAL CONTACT ON ONE SIDE, A FIRST STOPMEANS FACING THE BOWED VANE AND CARRYING AN ELECTRICAL CONTACT FORENGAGEMENT WITH THE ELECTRICAL CONTACT ON THE BOWED VANE, A SECOND STOPMEANS FACING THE OTHER SIDE OF THE BOWED VANE, A FIRST PULL MEANSCONNECTED BETWEEN THE FIXED SUPPORT AND THE MOVABLE MEMBER AT A POINTADJACENT THE PIVOTED END OF THE MOVABLE MEMBER TO EXERT A FORCE ON THEMOVABLE MEMBER WHICH CAN BE DECREASED BY HEATING THE FIRST PULL MEANSWITH ELECTRIC CURRENT AND WHICH TENDS TO PIVOT THE MOVABLE MEMBER AWAYFROM THE FIRST PULL MEANS, A SECOND PULL MEANS CONNECTED BETWEEN THEFIXED SUPPORT AND THE MOVABLE MEMBER AT A POINT ADJACENT THE PIVOTED ENDOF THE MOVABLE MEMBER TO EXERT A FORCE ON THE MOVABLE MEMBER WHICH CANBE DECREASED BY HEATING THE SECOND PULL MEANS WITH ELECTRIC CURRENT ANDWHICH OPPOSES THE FORCE EXERTED ON THE MOVABLE MEMBER BY THE FIRST PULLMEANS, A SOURCE OF ELECTRIC CURRENT CONNECTING IN SERIES WITH THE FIRSTAND SECOND PULL MEANS FOR HEATING THE SAME, SAID CONTACTS, WHEN INENGAGEMENT, SHUNTING SAID SECOND PULL MEANS TO CAUSE IN ALTERNATEHEATING AND COOLING OF THE FIRST AND SECOND PULL MEANS OUT OF PHASE WITHEACH OTHER AND THEREBY ALTERNATELY REVERSE THE BOW IN THE VANE BYALTERNATELY ING UP PRESSURE BETWEEN THE BOW AND THE FIRST AND SECONDSTOPS, AND A LAMP LOAD CONNECTED IN SERIES WITH SAID ELECTRIC CONTACTSACROSS SAID SOURCE OF ELECTRIC CURRENT SO THAT SAID LAMP LOAD WILL FLASHON AND OFF.